Certain classes of polymers having low dielectric constants can maintain their mechanical properties at exceptionally high temperatures, making them attractive for use in high-performance engineering thermoplastics. For example, polymers of the poly(aryl ether) family have been widely used, among other polymers incorporating the aryl ether subunit (polyetheretherketone, polysulphone, polyethersulphone, polyphenylene oxide, etc.), as dielectric coatings in the microelectronics industry due to their thermal and mechanical stability at high temperatures, as well as their relatively low dielectric constant (2.2-3.0).
Among the materials that may exhibit low dielectric constants may be fluorinated, organic polymers. However, fluorinated organic polymers may exhibit limited solubility, processability, and poor mechanical properties at elevated temperatures. For example, some fluorinated organic polymers have been shown to decompose at high temperatures, resulting in the release of corrosive gases, such as hydrogen fluoride or fluorine. Another approach for the lowering of the dielectric constant of materials may be the incorporation of pores in the dielectric material. While incorporation of pores within, for example, an organic polymer can lower the overall dielectric constant, the control of the porosity at a microscopic level may be difficult.
The incorporation of micropores has been shown to affect the mechanical properties of the coating. Previous work has shown that the incorporation of internal free volume at the molecular level by the use of rigid bicyclic scaffold that prevent the close-packing of adjacent polymer chains may also produce a material having a low dielectric constant without exhibiting some of the drawbacks associated with microporous structures. For example, poly(aryl ether)s obtained by the condensation of triptycene hydroquinones and decafluorobiphenyl were found to have low dielectric constant and promising thermomechanical properties. However, such materials may be difficult and costly to synthesize.
Accordingly, improved methods are needed.